Incandescent electric lamp



(No Model.)

T. A. EDISON.

INGANDESGENT ELECTRIC LAMP. No. 398,774. Patented Feb. 26, 1889 0 3.F/lyl 1 11313.

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UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OE MENLO PARK, NElV JERSEY.

INCANDESCENT ELECTRIC LAMP.

SIECIFICATION forming part of Letters Patent No. 398,774, dated February26, 1889.

Application filed May 14, 1883. Serial No. 94,891. (No model.)

In Fig. 3 the plate I) is inserted into the glass of the stem B, asbefore explained.

In Fig. 2 a short glass tube, F, is placed over one end of the filament.This would be placed over the filament before the latter is attached tothe lcading-in wires.

In Fig. 4 the disk of insulating material G is placed over the middle ofthe straight filament, being thus interposed between the terminalsthereof.

In my Patent No. 242,896 is shown a glass arm of small diameterextending up between the sides of the carbon loop to support the same.It is evident that this would not accomplish the object of the presentinvention, as the small glass arm would admit of the formation of theare around said arm.

lia-t I claim is 1. In an incandescing electric lamp, the combination,with the incandescin g conductor, of solid insulating materialinterposed between its terminals and adapted to prevent the formation ofan are between said termi- To aZZ whom it may concern.-

Be it known that I, THOMAS A. EDISON, of Menlo Park, in the county ofMiddlescx and State of New Jersey, have invented a new and usefulImprovement in Incandescent Electric Lamps, (Case No. 562,) of which thefollowing is a specification.

The object of this invention is to prevent the formation of an arebetween the terminals of the conductor within the globe of anincandescing electric lamp. I accomplish this by interposing between theterminals of the conductor an insulating body, preferably of atransparent material, like mica or glass. This of course increases theresistance of the space between the terminals and so prevents theformation of an arc across such space.

In applying the invention to a lamp in which an arched or looped carbonfilament is used I preferably place a thin plate of glass or micabetween the ends of the loop, rising to a su'fiicient height andsupported by a metallic or other arm rising from the middle of the innerstem or wire support of the lamp benals, substantially as set forth.tween the leading-in wires; or the edge of the 2. In an incandescingelectric lamp, the plate may be inserted in the stem, the glasscombination, with the arched or looped conbeing softened and split toadmit it; or I ductor, of an insulating-plate interposed bemay have oneend of the filament inclosed tween the terminals of said conductor andby a glass tube resting upon the glass below. adapted to prevent theformation of an arc \Vhen a straight carbon is employed, a between saidterminals, substantially as set glass or mica disk having an aperture inits forth. center maybe placed around the middle of 23. In anincandescing electric lamp, the the carbon, so that insulatirnl isinterposed combination, with the arched or looped conbet ween itsterminals. ductor and the glass stem or wire support, of

The invention is illustrated in the accoman insulating-plate interposedbetween the pany drawings, in which" terminals of said conductor andsupported l igure 1 is a view of an incandescing elec from said wiresupport and adapted to pretric lamp embodying the preferred form of ventthe formation of an arc between said my invention; Fig. 2, a view of aportion of terminals, substantially as set forth. the lamp with theglass tube inclosing the 4. In an incandescing electric lamp, the lowerportion of one side of the filament; combination, with the arched orlooped con- Fig. 3, a view showing the insulating-plate ductor and theglass stem or wire support, of inserted in the glass of the stem, andFig. 4 an insulating-plate having its edge inserted a view showing theinvcntiim applied to a in the glass of said support and extending up straight carbon lamp. 3 between the terminals of said conductor and .irepresents theinclosing-globeof the lamp, l adapted to prevent theformation of an arc and ll isthe inner stem sealed therein. The betweenthe terminals, substantially as set leading-in wires 1. 2 are sealed inthe glass forth. and support the tlmible carbon filament C, Thisspecification signed and witnessed this which is securcsl to said wiresby electroplat- 8th day of May, 1883.

'L F' I Tnos. A. EDISON.

Rclerring to l ig. l, l) is a plate oi glass or mica interposed betweenthe sides of the filament U and supported by an arm, E, rising from theglass of the stem B.

\Vitnesscs:

WM. H. MEAnowcRoE'r, H. W. SEEL'Y.

